Functional demo with a new TransposeCalculator

[ammatwain]

I have created a functional demo with a new TransposeCalculator.

Features:

• Transpose by Key and octave, with or without Key signature transposing;
• transpose by halftones, with or without Key signature transposing;
• transpose by interval, with or without Key signature transposing;
• in progress, transpose diatonically, without Key signature transposing (obviously).

You can find it at this URL:
https://ammatwain.github.io/extended-transpose-calculator/
This could potentially solve some OSMD issues related to transposition.
If you have some free time, please test it and let me know if you encounter any problems.
I need to gather positive feedback before making a pull request.
Thank you for your attention.
Amedeo

https://github.com/ammatwain

Originally posted by @ammatwain in #1391 (comment)

[sschmidTU]

This is looking very good so far! The ability to change the octaves is fantastic.

I've just noticed a small issue where the key signatures don't look correct if you transpose the default scale sample to G major in the second measure.

But admittedly that is also not a very common case.

A pull request eventually would be appreciated!

[ammatwain]

Hey Simon, you caught a bug right away! I want to assure you that the second key is correct, as Db is a homophonic key of C#, which is the MainKey of the score.
G does not have any homophonic key signatures. Therefore, when transposing from C# to G or from Db to G, both will be transposed to G.
However, the octave on which it transposes is wrong, and this represents an abnormal behavior that needs to be corrected urgently.

[ammatwain]

Problem on octave solved, I've sent you the pull request.

[ammatwain]

I believe I misunderstood your instruction. You were referring to the fact that the sharp symbol is on the wrong line of the "A" note, instead of "F," as if the Clef were for the violin and not for the bass. In this case, I assume (but I need to do some checking), that the issue lies upstream of the transposition system.